THE STOMACH ROUND WORMS. 

 Strongylus contortus, Eud. 



Plate XVIII. 



Strongylus contortus, or the twisted strougyle, is an inhabitant of the 

 fourth stomach of sheep and goats. Though iu the majority of flocks 

 it produces but little if auy disturbance, yet there are times wheu, in 

 connectiou with other species, it causes disease which may carry off 

 numbers of lambs. In the southwestern States and Territories the 

 disease has been called lombriz, a corruption of the Spanish word lombrici, 

 meaniug worms. The later writers seem to be inclined to attach a 

 specific meaniug to this word, while the Mexicans, who used it, merely 

 intended to say that the lambs died of worm disease. 



Description. — Female, 18 to '.W'"™ long; male, 15 to 20™™ long; body reddish; 

 iciuale ii.arked by a double spiral white line, thicker toward the caudal end. The 

 NJsiu shows eighteen longitudinal lines. The mouth is round and without visible lips 

 or papiliiB. The ueck has two barb-like side papilhe; unicellular glands scarcely 

 visible. The male is about two-thirds as long as the adult female, and shows no 

 spiral line. Bursa deeply bilobed, with a small dorsal lobe attached to one of the 

 pair. The lobes are somewhat longer than broad. The veutral costte are separated ; 

 the lateral are double and separated ; the dorsolateral is attached to the lateral group 

 near its base; the dorsal costie support the dorsal lobe and each brauch is double; 

 the twofold character is indicated by a little notch. The lateral cost;e are irregu- 

 larly divided, many variations being observed. Spicula two, embracing a chitinous 

 piece between them. They are short, cylindrical, barbed on one side near the eud, 

 and have blunt tips. Female: Vulva 3'"'" from the tail and covered by a nipple- 

 like projection, 0.5'"'" long ; the latter has thin borders, and is coucavo-convex, to fit 

 the body when pressed against it. Uteri two, each opening into the common vagina ; 

 one is anteriorly directed and the other posteriorly, with a short loop between it and 

 the vagina. The ovary of the posterior uterus is reflected anteriorly to rejoin its fel- 

 low, and together they wind spirally aiouud the dark-colored intestine. The ovoid 

 eggs are laid iu the gastrula form, or after they have passed through the segmenta- 

 tion stage; length, 0.070 to 0.097'^""; width, 0.043 to 0.054'°™. 



Occurrence. — This worm may be found in all stages in the fourth 

 stonjaeh or abomasum of sheep. Wheu collected immediately after 

 death from a slaughtered sheep they may be detected adhering by their 

 heads to the mucous membrane. They are then of a reddish color, which 

 may be because they feed iu part upou the blood of the victim. 



The life history of Stronf/ylus contortus seems to be apparently simple. 

 Among a number of lambs kept at the Experimental Station in 1888 

 were two or three which had been raised there. A post-mortem exami- 



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